* {
    padding: 0;
    margin: 0;
}

ul {
    display: flex;
    flex-direction: column;
    margin: 200px auto;
    width: 200px;
    height: 600px;
    border: 2px solid red;
}

li {
    width: 170px;
    height: 170px;
    margin: 15px 15px;
    list-style: none;
    border-radius: 50%;
    border: 3px solid yellow;
}